A CFD-based analysis to identify an optimal size and shape pattern that promotes the growth of a functional endothelial cell layer

This work represents a preliminary step of a wider study which aims to investigate the influence of substrate meso- and micro-topographies on the modulation of Wall Shear Stress (WSS), being this latter one of the key factor for promoting endothelial cell (EC) growth, proliferation, and stability. The ultimate goal of the study is to improve the performance and functionality of blood-contacting medical devices, which often fail due to thrombus formation and endothelial damage, necessitating lifelong anticoagulant treatments. A promising solution is to design device surfaces that support the formation of a stable endothelial layer, thereby improving hemocompatibility and reducing thrombogenic risks. Surface patterning is regarded as superior to biological and chemical functionalization, as it ensures long-term performance without degradation or loss of functionality over time, unlike conventional surface coatings. This study employed Computational Fluid Dynamics (CFD) simulations to predict the WSS under two hemodynamic conditions: constant and sinusoidal flow profiles. Although the present study was only limited to a square pattern geometry, three different depths patterns were simulated and metrics such as velocity and WSS were predicted and used to identify the optimal topographies for EC behaviour. Blood was modeled as a Newtonian fluid, and a fully hexahedral mesh ensured a fine computational accuracy. Simulations results revealed that patterns having the highest depth significantly reduced WSS due to fluid shielding effects. The analysed geometries exhibited good performance, maintaining WSS values within the physiological range, conducive to EC survival. These findings suggest that topographical depth is a critical parameter for creating niches that enhance endothelialization. Therefore, the simulated pattern was found to be adequate for sustaining EC integrity and stability. Future studies will address the analysis of other geometries (e.g., grooves, honeycombs, etc.) and flow conditions, coupled with cellular experiments, to validate the developed numerical models and to optimize designs further.